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Business Combinations, Net Assets Acquired and Estimated Fair Value Adjustments (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Oct. 10, 2018 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) Premises	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Fair Value Adjustments [Abstract]
Amortization of core deposit intangible		$ 228	$ 110	$ 13
Core Deposit Intangible [Member]
Fair Value Adjustments [Abstract]
Estimated useful life		10 years
Future estimated amortization expense on CDI [Abstract]
2019		$ 639
2020		626
2021		611
2022		593
2023		573
Thereafter		2,236
Total		$ 5,278
Bank of Rio Vista [Member]
Fair Value Adjustments [Abstract]
Loans	$ 440
Reversal of Allowance for Loan Loss	1,616
Core Deposit Intangible Asset	4,670
Other Assets & Liabilities, net	1,568
Total Purchase Accounting Adjustments	8,294
Deferred Tax Asset (tax effect of purchase accounting adjustments at 29.56%)	(2,452)
DTA Adjustment	(62)
Merger Consideration	41,647
Goodwill	$ 11,183
Percentage of tax effect of purchase accounting adjustments	29.56%
Future estimated amortization expense on CDI [Abstract]
Number of remaining shares of equity interest acquired (in shares) \| shares	2,414
Per share price of shares issued (in dollars per share) \| $ / shares	$ 8,200
Bank of Rio Vista [Member] \| Bank Premises [Member]
Future estimated amortization expense on CDI [Abstract]
Number of properties \| Premises		2
Ownership interest in properties		100.00%
Bank of Rio Vista [Member] \| Book Value [Member]
Net Assets Acquired and Estimated Fair Value Adjustments [Abstract]
Net Assets Acquired	$ 24,684
Fair Value Adjustments [Abstract]
Goodwill	0
Bank of Rio Vista [Member] \| Fair Value [Member]
Net Assets Acquired and Estimated Fair Value Adjustments [Abstract]
Net Assets Acquired	30,464
Fair Value Adjustments [Abstract]
Goodwill	$ 11,183
Bank of Rio Vista [Member] \| Core Deposit Intangible [Member]
Fair Value Adjustments [Abstract]
Estimated useful life		10 years
Amortization of core deposit intangible		$ 120
Future estimated amortization expense on CDI [Abstract]
2019		533
2020		524
2021		512
2022		499
2023		481
Thereafter		2,001
Total		$ 4,550